How Can Nutrition Research Better Reflect the Relationship Between Wasting and Stunting in Children? Learnings from the Wasting and Stunting Project.

Childhood wasting and stunting affect large numbers of children globally. Both are important risk factors for illness and death yet, despite the fact that these conditions can share common risk factors and are often seen in the same child, they are commonly portrayed as relatively distinct manifestations of undernutrition. In 2014, the Wasting and Stunting project was launched by the Emergency Nutrition Network. Its aim was to better understand the complex relationship and associations between wasting and stunting and examine whether current separations that were apparent in approaches to policy, financing, and programs were justified or useful. Based on the project's work, this article aims to bring a wasting and stunting lens to how research is designed and financed in order for the nutrition community to better understand, prevent, and treat child undernutrition. Discussion of lessons learnt focuses on the synergy and temporal relationships between children's weight loss and linear growth faltering, the proximal and distal factors that drive diverse forms of undernutrition, and identifying and targeting people most at risk. Supporting progress in all these areas requires research collaborations across interest groups that highlight the value of research that moves beyond a focus on single forms of undernutrition, and ensures that there is equal attention given to wasting as to other forms of malnutrition, wherever it is present.

Anthropometric criteria for best-identifying children at high risk of mortality: a pooled analysis of twelve cohorts.

OBJECTIVE: To understand which anthropometric diagnostic criteria best discriminate higher from lower risk of death in children and explore programme implications. DESIGN: A multiple cohort individual data meta-analysis of mortality risk (within 6 months of measurement) by anthropometric case definitions. Sensitivity, specificity, informedness and inclusivity in predicting mortality, face validity and compatibility with current standards and practice were assessed and operational consequences were modelled. SETTING: Community-based cohort studies in twelve low-income countries between 1977 and 2013 in settings where treatment of wasting was not widespread. PARTICIPANTS: Children aged 6 to 59 months. RESULTS: Of the twelve anthropometric case definitions examined, four (weight-for-age Z-score (WAZ) <-2), (mid-upper arm circumference (MUAC) <125 mm), (MUAC < 115 mm or WAZ < -3) and (WAZ < -3) had the highest informedness in predicting mortality. A combined case definition (MUAC < 115 mm or WAZ < -3) was better at predicting deaths associated with weight-for-height Z-score <-3 and concurrent wasting and stunting (WaSt) than the single WAZ < -3 case definition. After the assessment of all criteria, the combined case definition performed best. The simulated workload for programmes admitting based on MUAC < 115 mm or WAZ < -3, when adjusted with a proxy for required intensity and/or duration of treatment, was 1·87 times larger than programmes admitting on MUAC < 115 mm alone. CONCLUSIONS: A combined case definition detects nearly all deaths associated with severe anthropometric deficits suggesting that therapeutic feeding programmes may achieve higher impact (prevent mortality and improve coverage) by using it. There remain operational questions to examine further before wide-scale adoption can be recommended.

Prognostic value of different anthropometric indices over different measurement intervals to predict mortality in 6-59-month-old children.

OBJECTIVE: To compare the prognostic value of mid-upper arm circumference (MUAC), weight-for-height Z-score (WHZ) and weight-for-age Z-score (WAZ) for predicting death over periods of 1, 3 and 6 months follow-up in children. DESIGN: Pooled analysis of twelve prospective studies examining survival after anthropometric assessment. Sensitivity and false-positive ratios to predict death within 1, 3 and 6 months were compared for three individual anthropometric indices and their combinations. SETTING: Community-based, prospective studies from twelve countries in Africa and Asia. PARTICIPANTS: Children aged 6-59 months living in the study areas. RESULTS: For all anthropometric indices, the receiver operating characteristic curves were higher for shorter than for longer durations of follow-up. Sensitivity was higher for death with 1-month follow-up compared with 6 months by 49 % (95 % CI (30, 69)) for MUAC < 115 mm (P < 0·001), 48 % (95 % CI (9·4, 87)) for WHZ < -3 (P < 0·01) and 28 % (95 % CI (7·6, 42)) for WAZ < -3 (P < 0·005). This was accompanied by an increase in false positives of only 3 % or less. For all durations of follow-up, WAZ < -3 identified more children who died and were not identified by WHZ < -3 or by MUAC < 115 mm, 120 mm or 125 mm, but the use of WAZ < -3 led to an increased false-positive ratio up to 16·4 % (95 % CI (12·0, 20·9)) compared with 3·5 % (95 % CI (0·4, 6·5)) for MUAC < 115 mm alone. CONCLUSIONS: Frequent anthropometric measurements significantly improve the identification of malnourished children with a high risk of death without markedly increasing false positives. Combining two indices increases sensitivity but also increases false positives among children meeting case definitions.

How age and sex affect treatment outcomes for children with severe malnutrition: A multi-country secondary data analysis.

Age and sex influence the risk of childhood wasting. We aimed to determine if wasting treatment outcomes differ by age and sex in children under 5 years, enroled in therapeutic and supplementary feeding programmes. Utilising data from stage 1 of the ComPAS trial, we used logistic regression to assess the association between age, sex and wasting treatment outcomes (recovery, death, default, non-response, and transfer), modelling the likelihood of recovery versus all other outcomes. We used linear regression to calculate differences in mean length of stay (LOS) and mean daily weight gain by age and sex. Data from 6929 children from Kenya, Chad, Yemen and South Sudan was analysed. Girls in therapeutic feeding programmes were less likely to recover than boys (pooled odds ratio [OR]: 0.84, 95% confidence interval [CI]: 0.72-0.97, p = 0.018). This association was statistically significant in Chad (OR: 0.61, 95% CI: 0.39-0.95, p = 0.030) and Yemen (OR: 0.47, 95% CI: 0.27-0.81, p = 0.006), but not in Kenya and South Sudan. Multinomial analysis, however, showed no difference in recovery between sexes. There was no difference between sexes for LOS, but older children (24-59 months) had a shorter mean LOS than younger children (6-23 months). Mean daily weight gain was consistently lower in boys compared with girls. We found few differences in wasting treatment outcomes by sex and age. The results do not indicate a need to change current programme inclusion requirements or treatment protocols on the basis of sex or age, but future research in other settings should continue to investigate the aetiology of differences in recovery and implications for treatment protocols.

How do children with severe underweight and wasting respond to treatment? A pooled secondary data analysis to inform future intervention studies.

Children with weight-for-age z-score (WAZ) <-3 have a high risk of death, yet this indicator is not widely used in nutrition treatment programming. This pooled secondary data analysis of children aged 6-59 months aimed to examine the prevalence, treatment outcomes, and growth trajectories of children with WAZ <-3 versus children with WAZ ≥-3 receiving outpatient treatment for wasting and/or nutritional oedema, to inform future protocols. Binary treatment outcomes between WAZ <-3 and WAZ ≥-3 admissions were compared using logistic regression. Recovery was defined as attaining mid-upper-arm circumference ≥12.5 cm and weight-for-height z-score ≥-2, without oedema, within a period of 17 weeks of admission. Data from 24,829 children from 9 countries drawn from 13 datasets were included. 55% of wasted children had WAZ <-3. Children admitted with WAZ <-3 compared to those with WAZ ≥-3 had lower recovery rates (28.3% vs. 48.7%), higher risk of death (1.8% vs. 0.7%), and higher risk of transfer to inpatient care (6.2% vs. 3.8%). Growth trajectories showed that children with WAZ <-3 had markedly lower anthropometry at the start and end of care, however, their patterns of anthropometric gains were very similar to those with WAZ ≥-3. If moderately wasted children with WAZ <-3 were treated in therapeutic programmes alongside severely wasted children, we estimate caseloads would increase by 32%. Our findings suggest that wasted children with WAZ <-3 are an especially vulnerable group and those with moderate wasting and WAZ <-3 likely require a higher intensity of nutritional support than is currently recommended. Longer or improved treatment may be necessary, and the timeline and definition of recovery likely need review.

Anthropometric deficits and the associated risk of death by age and sex in children aged 6-59 months: A meta-analysis.

Risk of death from undernutrition is thought to be higher in younger than in older children, but evidence is mixed. Research also demonstrates sex differences whereby boys have a higher prevalence of undernutrition than girls. This analysis described mortality risk associated with anthropometric deficits (wasting, underweight and stunting) in children 6-59 months by age and sex. We categorised children into younger (6-23 months) and older (24-59 months) age groups. Age and sex variations in near-term (within 6 months) mortality risk, associated with individual anthropometric deficits were assessed in a secondary analysis of multi-country cohort data. A random effects meta-analysis was performed. Data from seven low-or-middle-income-countries collected between 1977 and 2013 were analysed. One thousand twenty deaths were recorded for children with anthropometric deficits. Pooled meta-analysis estimates showed no differences by age in absolute mortality risk for wasting (RR 1.08, p = 0.826 for MUAC < 125 mm; RR 1.35, p = 0.272 for WHZ < -2). For underweight and stunting, absolute risk of death was higher in younger (RR 2.57, p < 0.001) compared with older children (RR 2.83, p < 0.001). For all deficits, there were no differences in mortality risk for girls compared with boys. There were no differences in the risk of mortality between younger and older wasted children, supporting continued inclusion of all children under-five in wasting treatment programmes. The risk of mortality associated with underweight and stunting was higher among younger children, suggesting that prevention programmes might be justified in focusing on younger children where resources are limited. There were no sex differences by age in mortality risk for all deficits.

Changing sex differences in undernutrition of African children: findings from Demographic and Health Surveys.

The study investigates sex differences in the prevalence of undernutrition in sub-Saharan Africa. Undernutrition was defined by Z-scores using the CDC-2000 growth charts. Some 128 Demographic and Health Surveys (DHS) were analysed, totalling 700,114 children under-five. The results revealed a higher susceptibility of boys to undernutrition. Male-to-female ratios of prevalence averaged 1.18 for stunting (height-for-age Z-score <-2.0); 1.01 for wasting (weight-for-height Z-score <-2.0); 1.05 for underweight (weight-for-age Z-score <-2.0); and 1.29 for concurrent wasting and stunting (weight-for-height and height-for-age Z-scores <-2.0). Sex ratios of prevalence varied with age for stunting and concurrent wasting and stunting, with higher values for children age 0-23 months and lower values for children age 24-59 months. Sex ratios of prevalence tended to increase with declining level of mortality for stunting, underweight and concurrent wasting and stunting, but remained stable for wasting. Comparisons were made with other anthropometric reference sets (NCHS-1977 and WHO-), and the results were found to differ somewhat from those obtained with CDC-2000. Possible rationales for these patterns are discussed.

Factors associated with concurrent wasting and stunting among children 6-59 months in Karamoja, Uganda.

Children with concurrent wasting and stunting (WaSt) and children with severe wasting have a similar risk of death. Existing evidence shows that wasting and stunting share similar causal pathways, but evidence on correlates of WaSt remains limited. Research on correlates of WaSt is needed to inform prevention strategies. We investigated the factors associated with WaSt in children 6-59 months in Karamoja Region, Uganda. We examined data for 33,054 children aged 6-59 months using June 2015 to July 2018 Food Security and Nutrition Assessment in Karamoja. We defined WaSt as being concurrently wasted (weight-for-height z-scores <-2.0) and stunted (height-for-age z-score <-2.0). We conducted multivariate mixed-effect logistic regression to assess factors associated with WaSt. Statistical significance was set at p < 0.05. In multivariate analysis, being male (adjusted odds ratio [aOR] = 1.79; 95% confidence interval [CI] [1.60-2.00]), aged 12-23 months (aOR = 2.25; 95% CI [1.85-2.74]), 36-47 months (aOR = 0.65; 95% CI [0.50-0.84]) and 48-59 months (aOR = 0.71; 95% CI [0.54-0.93]) were associated with WaSt. In addition, acute respiratory infection (aOR = 1.30; 95% CI [1.15-1.48]), diarrhoea (aOR = 1.25; 95% CI [1.06-1.48]) and malaria/fever (aOR = 0.83; 95% CI [0.73-0.96]) episodes were associated with WaSt. WaSt was significantly associated with maternal underweight (body mass index <18.5 kg/m2 ), short stature (height <160 cm), low mid-upper arm circumference (MUAC <23 cm) and having ≥4 live-births. WaSt was prevalent in households without livestock (aOR = 1.30; 95% CI [1.13-1.59]). Preventing the occurrence of WaSt through pragmatic and joint approaches are recommended. Future prospective studies on risk factors of WaSt to inform effective prevention strategies are recommended.

Concurrently wasted and stunted children 6-59 months in Karamoja, Uganda: prevalence and case detection.

We assessed prevalence of concurrently wasted and stunted (WaSt) and explored the overlaps between wasted, stunted, underweight and low mid-upper arm circumference (MUAC) among children aged 6-59 months in Karamoja, Uganda. We also determined optimal weight-for-age (WAZ) and MUAC thresholds for detecting WaSt. We conducted secondary data analysis with 2015-2018 Food Security and Nutrition Assessment (FSNA) cross-sectional survey datasets from Karamoja. Wasting, stunting and underweight were defined as <-2.0 z-scores using WHO growth standards. Low MUAC was defined as <12.5 cm. We defined WaSt as concurrent wasting and stunting. Prevalence of WaSt was 4.96% (95% CI [4.64, 5.29]). WaSt was more prevalent in lean than harvest season (5.21% vs. 4.53%; p = .018). About half (53.92%) of WaSt children had low MUAC, and all were underweight. Younger children aged <36 months had more WaSt, particularly males. Males with WaSt had higher median MUAC than females (12.50 vs. 12.10 cm; p < .001). A WAZ <-2.60 threshold detected WaSt with excellent sensitivity (99.02%) and high specificity (90.71%). MUAC threshold <13.20 cm had good sensitivity (81.58%) and moderate specificity (76.15%) to detect WaSt. WaSt prevalence of 5% is a public health concern, given its high mortality risk. All children with WaSt were underweight and half had low MUAC. WAZ and MUAC could be useful tools for detecting WaSt. Prevalence monitoring and prospective studies on WAZ and MUAC cut-offs for WaSt detection are recommended. Future consideration to integrate WAZ into therapeutic feeding programmes is recommended to detect and treat WaSt children.

Disability-adjusted life years for severe acute malnutrition: implications of alternative model specifications.

OBJECTIVE: Reducing the burden of childhood severe acute malnutrition (SAM) is key to improving global child health outcomes. Assessing cost-effectiveness of nutrition interventions remains an important evidence gap. Disability-adjusted life years (DALYs) are a common indicator used in cost-effectiveness analyses. DALYs were established by the Global Burden of Disease (GBD) study. Recent iterations of the GBD have changed the methods used to calculate DALYs by dropping age-weighting and discounting (AD) and updating disability weights (DW). Cost-effectiveness analyses may use either local or international standard life expectancies (LE). Changes in model specifications for calculating DALYs may have implications for cost-effectiveness analyses using DALYs, interpreting historical DALY estimates, and related resource allocation decisions. The present study aimed to quantify the magnitude of change in estimates of DALYs attributable to SAM given recent methodological changes. DESIGN: From secondary data analysis, using parameter values from routine programme monitoring data for two SAM treatment programmes and published literature, eight calculation models were created to estimate DALYs with and without AD, using different sets of DW, and local v. standard LE. RESULTS: Different DW had a marginal effect on DALY estimates. Different LE had a small effect when AD was used, but a large effect when AD was not used. CONCLUSIONS: DALY estimates are sensitive to the model used. This complicates comparisons between studies using different models and needs to be accounted for in decision making. It seems sensible for analyses to report results using models with and without AD and using local and standard LE.

Improving screening for malnourished children at high risk of death: a study of children aged 6-59 months in rural Senegal.

OBJECTIVE: To investigate whether children with concurrent wasting and stunting require therapeutic feeding and to better understand whether multiple diagnostic criteria are needed to identify children with a high risk of death and in need of treatment. DESIGN: Community-based cohort study, following 5751 children through time. Each child was visited up to four times at 6-month intervals. Anthropometric measurements were taken at each visit. Survival was monitored using a demographic surveillance system operating in the study villages. SETTING: Niakhar, a rural area of the Fatick region of central Senegal.ParticipantsChildren aged 6-59 months living in thirty villages in the study area. RESULTS: Weight-for-age Z-score (WAZ) and mid-upper arm circumference (MUAC) were independently associated with near-term mortality. The lowest WAZ threshold that, in combination with MUAC, detected all deaths associated with severe wasting or concurrent wasting and stunting was WAZ <-2·8. Performance for detecting deaths was best when only WAZ and MUAC were used. Additional criteria did not improve performance. Risk ratios for near-term death in children identified using WAZ and MUAC suggest that children identified by WAZ <-2·8 but with MUAC≥115 mm may require lower-intensity treatment than children identified using MUAC <115 mm. CONCLUSIONS: A combination of MUAC and WAZ detected all near-term deaths associated with severe anthropometric deficits including concurrent wasting and stunting. Therapeutic feeding programmes may achieve higher impact if WAZ and MUAC admission criteria are used.

Concurrent wasting and stunting among under-five children in Niakhar, Senegal.

The study describes the patterns of concurrent wasting and stunting (WaSt) among children age 6-59 months living in the 1980s in Niakhar, a rural area of Senegal under demographic surveillance. Wasting and stunting were defined by z scores lower than -2 in weight for height and height for age. Both conditions were found to be highly prevalent, wasting more so before age 30 months, stunting more so after age 30 months. As a result, concurrent WaSt peaked around age 18 months and its prevalence (6.2%) was primarily the product of the two conditions, with an interaction term of 1.57 (p < 10-6 ). The interaction was due to the correlation between both conditions (more stunting if wasted, more wasting if stunted). Before age 30 months, boys were more likely to be concurrently wasted and stunted than girls (RR = 1.61), but the sex difference disappeared after 30 months of age. The excess susceptibility of younger boys could not be explained by muscle mass or fat mass measured by arm or muscle circumference, triceps, or subscapular skinfold. Concurrent WaSt was a strong risk factor for child mortality, and its effect was the product of the independent effect of each component, with no significant interaction.

Recovery and relapse from severe acute malnutrition after treatment: a prospective, observational cohort trial in Pakistan.

OBJECTIVE: Millions of children suffer from severe acute malnutrition (SAM) in low- and middle- income countries. Much is known about the effectiveness of community treatment programmes (CMAM) but little is known about post-discharge outcomes after successful treatment. The present study aimed to evaluate post-discharge outcomes of children cured of SAM. DESIGN: Prospective, observational cohort study. Children with SAM who were discharged as cured were followed monthly for 6 months or until they experienced relapse to SAM. 'Cure' was defined as a child achieving a mid-upper arm circumference (MUAC) of ≥115 mm with ≥15 % weight gain after loss of oedema. Relapse was defined as a child with MUAC<115 mm and/or oedema at any monthly visit. SETTING: Save the Children CMAM programme in Swabi, Pakistan, from January 2012 to December 2014. SUBJECTS: Children aged 6-59 months (n 117) discharged as cured from the CMAM programme were eligible for the study and followed for 6 months. RESULTS: One hundred children (92·6 %) remained free of SAM, eight (7·4 %) relapsed to SAM, nine (8·3 %) were lost to follow-up and none died. Most relapses occurred within 3 months of discharge (mean time to relapse 73·4 (sd 36·2) d). At enrolment, 90 % had moderate acute malnutrition (MAM) and 10 % were not malnourished. By the end of 6 months, 35 % persisted with MAM and the remaining were not malnourished. CONCLUSIONS: In rural Pakistan, fewer than 10 % of children cured of SAM relapsed. The first 3 months is the most vulnerable time.

Assessing Coverage of Population-Based and Targeted Fortification Programs with the Use of the Fortification Assessment Coverage Toolkit (FACT): Background, Toolkit Development, and Supplement Overview.

Food fortification is a widely used approach to increase micronutrient intake in the diet. High coverage is essential for achieving impact. Data on coverage is limited in many countries, and tools to assess coverage of fortification programs have not been standardized. In 2013, the Global Alliance for Improved Nutrition developed the Fortification Assessment Coverage Toolkit (FACT) to carry out coverage assessments in both population-based (i.e., staple foods and/or condiments) and targeted (e.g., infant and young child) fortification programs. The toolkit was designed to generate evidence on program coverage and the use of fortified foods to provide timely and programmatically relevant information for decision making. This supplement presents results from FACT surveys that assessed the coverage of population-based and targeted food fortification programs across 14 countries. It then discusses the policy and program implications of the findings for the potential for impact and program improvement.

Coverage of Large-Scale Food Fortification of Edible Oil, Wheat Flour, and Maize Flour Varies Greatly by Vehicle and Country but Is Consistently Lower among the Most Vulnerable: Results from Coverage Surveys in 8 Countries.

Background: Large-scale food fortification (LSFF) of commonly consumed food vehicles is widely implemented in low- and middle-income countries. Many programs have monitoring information gaps and most countries fail to assess program coverage.Objective: The aim of this work was to present LSFF coverage survey findings (overall and in vulnerable populations) from 18 programs (7 wheat flour, 4 maize flour, and 7 edible oil programs) conducted in 8 countries between 2013 and 2015.Methods: A Fortification Assessment Coverage Toolkit (FACT) was developed to standardize the assessments. Three indicators were used to assess the relations between coverage and vulnerability: 1) poverty, 2) poor dietary diversity, and 3) rural residence. Three measures of coverage were assessed: 1) consumption of the vehicle, 2) consumption of a fortifiable vehicle, and 3) consumption of a fortified vehicle. Individual program performance was assessed based on the following: 1) achieving overall coverage ≥50%, 2) achieving coverage of ≥75% in ≥1 vulnerable group, and 3) achieving equity in coverage for ≥1 vulnerable group.Results: Coverage varied widely by food vehicle and country. Only 2 of the 18 LSFF programs assessed met all 3 program performance criteria. The 2 main program bottlenecks were a poor choice of vehicle and failure to fortify a fortifiable vehicle (i.e., absence of fortification).Conclusions: The results highlight the importance of sound program design and routine monitoring and evaluation. There is strong evidence of the impact and cost-effectiveness of LSFF; however, impact can only be achieved when the necessary activities and processes during program design and implementation are followed. The FACT approach fills an important gap in the availability of standardized tools. The LSFF programs assessed here need to be re-evaluated to determine whether to further invest in the programs, whether other vehicles are appropriate, and whether other approaches are needed.

Coverage of Nutrition Interventions Intended for Infants and Young Children Varies Greatly across Programs: Results from Coverage Surveys in 5 Countries.

Background: The efficacy of a number of interventions that include fortified complementary foods (FCFs) or other products to improve infant and young child feeding (IYCF) is well established. Programs that provide such products free or at a subsidized price are implemented in many countries around the world. Demonstrating the impact at scale of these programs has been challenging, and rigorous information on coverage and utilization is lacking.Objective: The objective of this article is to review key findings from 11 coverage surveys of IYCF programs distributing or selling FCFs or micronutrient powders in 5 countries.Methods: Programs were implemented in Ghana, Cote d'Ivoire, India, Bangladesh, and Vietnam. Surveys were implemented at different stages of program implementation between 2013 and 2015. The Fortification Assessment Coverage Toolkit (FACT) was developed to assess 3 levels of coverage (message: awareness of the product; contact: use of the product ≥1 time; and effective: regular use aligned with program-specific goals), as well as barriers and factors that facilitate coverage. Analyses included the coverage estimates, as well as an assessment of equity of coverage between the poor and nonpoor, and between those with poor and adequate child feeding practices.Results: Coverage varied greatly between countries and program models. Message coverage ranged from 29.0% to 99.7%, contact coverage from 22.6% to 94.4%, and effective coverage from 0.8% to 88.3%. Beyond creating awareness, programs that achieved high coverage were those with effective mechanisms in place to overcome barriers for both supply and demand.Conclusions: Variability in coverage was likely due to the program design, delivery model, quality of implementation, and product type. Measuring program coverage and understanding its determinants is essential for program improvement and to estimate the potential for impact of programs at scale. Use of the FACT can help overcome this evidence gap.

Using cross-sectional surveys to estimate the number of severely malnourished children needing to be enrolled in specific treatment programmes.

OBJECTIVE: When planning severe acute malnutrition (SAM) treatment services, estimates of the number of children requiring treatment are needed. Prevalence surveys, used with population estimates, can directly estimate the number of prevalent cases but not the number of subsequent incident cases. Health managers often use a prevalence-to-incidence conversion factor (J) derived from two African cohort studies to estimate incidence and add the expected number of incident cases to prevalent cases to estimate expected SAM caseload for a given period. The present study aimed to estimate J empirically in different contexts. DESIGN: Observational study, with J estimated by correlating expected numbers of children to be treated, based on prevalence surveys, population estimates and assumed coverage, with the observed numbers of SAM patients treated. SETTING: Survey and programme data from six African and Asian countries. SUBJECTS: Twenty-four data sets including prevalence surveys and programme admissions data for 5 months following the survey. RESULTS: A statistically significant relationship between the number of SAM cases admitted to SAM treatment services and the estimated burden of SAM from prevalence surveys was found. Estimate for the slope (intercept forced to be zero) was 2·17 (95 % CI 1·33, 3·79). Estimates for the prevalence-to-incidence conversion factor J varied from 2·81 to 11·21, assuming programme coverage of 100 % and 38 %, respectively. CONCLUSIONS: Estimation of expected caseload from prevalence may require revision of the currently used prevalence-to-incidence conversion factor J of 1·6. Appropriate values for J may vary between different locations.

Improving Estimates of Numbers of Children With Severe Acute Malnutrition Using Cohort and Survey Data.

Severe acute malnutrition (SAM) is reported to affect 19 million children worldwide. However, this estimate is based on prevalence data from cross-sectional surveys and can be expected to miss some children affected by an acute condition such as SAM. The burden of acute conditions is more appropriately represented by cumulative incidence data. In the absence of incidence data, a method for burden estimation has been proposed that corrects available prevalence estimates to account for incident cases using an "incidence correction factor." We used data from 3 West African countries (Mali, Niger, and Burkina Faso, 2009-2012) to test the hypothesis that a single incidence correction factor may be used for estimation of SAM burden. We estimated the incidence correction factor and performed meta-analysis to calculate summary estimates for each country and for all 3 countries. Heterogeneity between countries and years was assessed using the I2 statistic. We estimated a pooled incidence correction factor of 4.82 (95% confidence interval: 3.15, 7.38), although there was substantial between-country heterogeneity (I2 = 69%). Knowing how many children in a particular area will be malnourished is fundamental to planning an effective operational response. Our results show that the incidence correction factor varies widely and suggest that estimating the burden of SAM with a common incidence correction factor is unlikely to be adequate.

Nutrition surveillance using a small open cohort: experience from Burkina Faso.

BACKGROUND: Nutritional surveillance remains generally weak and early warning systems are needed in areas with high burden of acute under-nutrition. In order to enhance insight into nutritional surveillance, a community-based sentinel sites approach, known as the Listening Posts (LP) Project, was piloted in Burkina Faso by Action Contre la Faim (ACF). This paper presents ACF's experience with the LP approach and investigates potential selection and observational biases. METHODS: Six primary sampling units (PSUs) were selected in each livelihood zone using the centric systematic area sampling methodology. In each PSU, 22 children aged between 6 and 24 months were selected by proximity sampling. The prevalence of GAM for each month from January 2011 to December 2013 was estimated using a Bayesian normal-normal conjugate analysis followed by PROBIT estimation. To validate the LP approach in detecting changes over time, the time trends of MUAC from LP and from five cross-sectional surveys were modelled using polynomial regression and compared by using a Wald test. The differences between prevalence estimates from the two data sources were used to assess selection and observational biases. RESULTS: The 95 % credible interval around GAM prevalence estimates using LP approach ranged between +6.5 %/-6.0 % on a prevalence of 36.1 % and +3.5 %/-2.9 % on a prevalence of 10.8 %. LP and cross-sectional surveys time trend models were well correlated (p = 0.6337). Although LP showed a slight but significant trend for GAM to decrease over time at a rate of -0.26 %/visit, the prevalence estimates from the two data sources showed good agreement over a 3-year period. CONCLUSIONS: The LP methodology has proved to be valid in following trends of GAM prevalence for a period of 3 years without selection bias. However, a slight observational bias was observed, requiring a periodical reselection of the sentinel sites. This kind of surveillance project is suited to use in areas with high burden of acute under-nutrition where early warning systems are strongly needed. Advocacy is necessary to develop sustainable nutrition surveillance system and to support the use of surveillance data in guiding nutritional programs.